Home / 1,121.15-1,680.70-687.35

Finding the Fourth Proportional to 1,121.15, 1,680.70 and 687.35

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Solution

The fourth proportional to 1,121.15, 1,680.70 and 687.35 is: 1,030.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.15 : 1,680.70 = 687.35 : x
  2. Step 2: Convert to fraction form
    1,121.15/1,680.70 = 687.35/x
  3. Step 3: Cross multiply
    1,121.15x = 1,680.70 × 687.35
  4. Step 4: Simplify right side
    1,121.15x = 1,155,229.15
  5. Step 5: Solve for x
    x = 1,155,229.15/1,121.15
  6. Step 6: Final answer
    x = 1,030.40

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.